Cross multiplying is when you multiply by 1 but change 1 to the form a/a where a is the bottom of the other fraction:

First multiply by to give a denominator of 12. This will make it easier to multiply later

As the last two terms have an equal denominator we can combine and simplify

Now we multiply each by the other's denominator to give them the same denominator

Now they have the same denominator we can combine

which is the answer